Manual control mechanism



May 5 1941 R. H. WHEMPNER 2,420,214

MANUAL @omnoh mczmmsu Filed oct. 14, 1942 f Gitorneg f -pmed n., 6,19412,420,214.

UNITED STATES PATENT ortica 2,420,214 p MANUAL coN'rnoL MEcnANTsMRussell H. Whempncr, Minneapolis, Minn., as-

signor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., acorporation of Delaware Application October 14, 1942, Serial No.461,954Y

. 12 Claims. (Cl. 236-1) l i 2 The present invention relates to theprovision by which the apparatus to be positioned may be of manual meansin conjunction with a device operatively disconnected from the powermeans which is normally positioned by a power means, for such device,then positioned by the manual the manual means being so arranged thatAthe means as desired and to later operate to discondevice may bemanually positioned entirely in- 5 nect the manual means and'a'galnplace the dedependently of the power means should occasion vice to bepositioned under the control of the Mise. power means.

l'n systems of control where a device to be It is a further object ofthe present invention to positioned is normally positioned by a powerprovide a single manual operator which may be means, it is oftendesirable to provide an arrangel0 operated to disconnect the power meansfrom a ment by which the device may be manually posidevice to bepositioned, to then position the detioned entirely independently of thepower vice manually in any of the positions to which means. For example,if the power means should it can normally be driven by the power means,be of the electrical type and become inoperative and nally to disconnectthe manual means and because of a failure of electrical power or for anyreconnect the power means to the device. other reason, the provision ofsuch manual means Another object ofthe invention is the provision makesit possible to nevertheless position the of manual disconnecting andpositioning means device to be controlled. Such an arrangement foradevice that is normally positioned by a has particular utility insystems of automatic power means, together with means for drivingcontrol used in aircraft and the like. The presthe power means to apredetermined position ent invention is disclosed in connection with anupon its disconnection and provided it is in opalrcraft temperaturecontrol system wherein the erative condition, the power meansautomatically temperature changing vmeans is automatically beingrecoupled to the device to be positioned controlled through reversibleelectric motor when moved to such predetermined position upon means andan electronic amplifier. In the event placing of the manual means in aselected posiof failure of electrical power or failure of the tion. Inother Words, it is an object of this inamplier or any of the tubestherein, or for that vention to provide a system of the type describedmatter failure from any cause of the automatic wherein placing of themanual means in a selectsystem of control, the present invention permitsed position automatically causes the power means manual actuation of thetemperature changing to resume control of the device to be controlledmeans completely independent of the automatic provided the power meansis in operating concontrol system through a mechanical connectiondition, between the manual operator and the apparatus Another object ofthe present invention is the tobe controlled and entirelyindependentlyof the provision of a single manual operator for a dereversibleelectrical motor power means. vice that is normally positioned by powermeans,

Although the invention is disclosed in conwhich manual operator has anormal inactive nection with `temperature control of theinteriorposition and which, upony movement out of said of the aircraft, it willreadily be seen that it is normal inactiveposition takes over control ofequally applicable to temperature control of the the device to bepositioned and retains such conengines or to the control of otherworking and 4o trol until the lmanual operator is moved back tooperating parts of the aircraft wherein it might the normal inactiveposition, whereupon the conwell be disastrous if the automatic controlsystrol of the device to be positioned is automatically tem failed andthere were no means of taking returned to the power means provided thepower over control manually. means is in operating condition.

Furthermore, in view of the large number of Additional objects of theinvention will become things which the pilot of an aircraft has to do,clear upon a reading of the following description it is highly desirablethat the manual control and appended claims in connection with the5inmeans be as simple and fool-proof as possible and gle drawing whereinan apparatus illustrative of require a minimum number of operations toplace my invention is shown applied to an automatic the manual controlmeans in control of the system of temperature control for an aircraftmechanism to be positioned and thereafter to re- Turning now to theSingle ligure of the drawing, turn contr-01 to the automatiesystem, Vadevice or armP i0 may be considered as the It therefore follows that oneof the objects of apparatus 'G0 be pOSitOned- This afm l0 isn0fthefpresem; invention is the provision, in a power mally positionedby an electric motor Il under operatcdremotecontrol system, of manualmeans the control of a suitable control system. The

electric motor II "s suitably connected to a redriven arm Il, is adaptedto slide along the ducing gear train I2 which in turn drives a finalresistance 32. driven shaft I3. The shaft I3 is indicated as Variationsin the bridge circuit N are transbeing journalled in a base plate I4,only one formed into movements of the electrical motor of which is shownfor purposes of clarity. It will 5 I I through the medium of anelectronic ampller be understood, however, that the shaft I3 will 38.This electronic amplifier preferably takes the be provided with asuitable number of bearings. form disclosed in Figure 1 ot theapplication of Further, the gear train I2 and motor II in actual AlbelfP- UDOD, Serial No. 437,581, filed April construction can convenientlybe mounted on the 3. 1942. The electronic amplifier is furnishedunderside of the base plate Il so that the com- 10 with any suitablesourcel o! alternating current plete mechanism constitutes a unitaryself-con- 15 indicated by the WL3S 39. The mplior n tained structure. Adriving arm I5 is secured 1S provided with a Dir 0f power Supplyterminals to a hub I6 that is in turn secured to the shaft u and i forthe bridge 23. The terminal ll is i3 by a Sei; screw |1, connected to abridge input terminal I2 which rrho driven arm lu constitutes onextension of Connects those arms of the bridge containing the asubstantially circular plate I8 which is in turn temperature Sensitiveresistance 2'I and the fixed secured, as by rivets I9, to asubstantially circular resistance 23. by means of Wire u. Silniliil'iy,Aplate 20. These integral plates and I8 are the erminal i in Connectedt'o 8 bridge input journalled on or concentrically with shaft I3 butterminal u formed by the junction of those 811118 are free to rotateindependently of such shaft. 20 Containing the fixed YCSiSCBIlOeS 29 and30. by In order to show certain of the other parts to be means 0f a Wire5- The iGWel' 6nd of the nXod later described, the plate 20 has beenbroken fesistanco 23 iS Connected to the Tight-hand ond mifbalanclgffieibised it Under normal conditions, the driving arm I5 @Weren 0 S r is coupled or clutched to the driven arm I0. To lefthand end 0f'balancing resistance n by a this end a driving ioioii 2i is pivoted onthe Wife 45- The amplifier n 1S further Provided driving arm i5 by a pin22. This driving latch with a pair of amplifier input terminals 48 and2i is provided with o ioioiiing portion 23 that 9- The terminal 4 isczfnntldio an Oggi: is normally engaged in a notch 24 formed in terminal9 of the bridge W c tum the plate M A spring 25, which has one end theJunction of those arms containing the temsecured t0 the driving arm I5and its other end pieature asnst'ie resmtate nisaggebnxl; secured to thedriving latch 2i, normally biases s s ance s conne on y the iaioiiingportion 2a of ino driving ioioii 2i 01 dwife 5tmig?" Sunsg dg: in such adirection as tocause it to enter the S er. con act w c rms I t H notoh Moutput terminal, by a wire 5 I'he mo or l d drivin wer ls It should nowbe readily apparent that with lrlfisi stlel; :geeltmmc aglgner n theparts thus far described in the positions through the wires n n and ushown movements of the electric motor I I are r vi e directlytransmitted to the driven arm I0 through 4o wilhlfggulsvonvlolg's' ofcoremdf "allie driving arm I5 and associated driving latch ings isconstantly energized The other winding 2 l h the brid e is balanced.

The motor I! may be controlled in any desired ogsripzg uigblancing of ebridge in one manne? either manually or automatically and direction, thesecond motor winding is energized is herein shown as controlled inaccordance with with a current having a leading phase in r 1 cttemprature Variations The temperature re' to the constantly energizedwinding. This causes sponsivelmeans 1s here shown as the well-knownmotor rotation in one direction when the bridge temperature responsiveresistance 21 which is of is unbalanced in the opposite direction, theSecond the usual type in that its resistance increases Winding of the5pm phase motor H is energized on temperature rise. This temperaturesensitive with a current having a lagging phase m respect resistance 2icomprises one arm of a bridge cirto that which energizes the constantlyenergized cuit 26. A second arm of the bridge circuit in- Winding Thiscauses rotation of motor 'l in the cludes a fixed resistance 28 andalthird arm of opposite direction All this is accomplished by the bridgecircuit includes a similar fixed rethe electronic amplmer 33 and themeans by slsitlmce 291 T he fourth and last arm 0f the 55 whichthisisaccomplishedisthoroughly described bridge circuit includes a fixedresistance 30 in in the Upton application heretofore referred to serieswith a fixed resistance 3i that is normally 0f Course, any other knownsystem for obtaining shunted in a manner which will be described reversemovements of motor II upon changes in hereinafter. Therefore, for thepresent purposes temperature may be utilized the bridge circuit may beconsidered as com- 6c The driven arm In may be used to position anyDrisrlg three arms having similar resistances 28, desired device orapparatus and in an aircraft 29 and 3G therein and a fourth arm havingthe temperature control system might position, for temperature sensitiveresistance 21 therein. example, a heat controlling valve or damper.

The arms 28 and 29 further include variable With the parts in theposition shown, the driven portions oiv a balancing or follow-upresistance. arm I0 is engaging a stop 55 and is therefore in Thisresistance is shown as a coiled wire 32 which one of its extremepositions. In this extreme is wound upon a rod of insulating material orposition, the valve or damper of the heat controlthe like 33 having anarcuate configuration. ling system is so positioned that no heat isbeing One end of the rod 33 is secured to the base plate supplied to theaircraft. The temperature within I4 by a fastening means 34. Similarly,the other 70 the aircraft is at or above the desired maximum. end of therod 33 is secured to the base plate Assuming that the temperature in theaircraft i4 by a fastening means 35. This balancing refalls below theIfic-.fired maximum, the resistance sistanee 32 lies in front of thedriven arm l0. of temperature sensitive resistance 21 decreases. Aslider contact 36, which is secured to a piece This causes an imbalancein the bridge circuit of insulating material 31 in turn carried by the75 26 that in turn is transmitted to the electronic amplier 38. Suchunbalance in the bridge circuit causes the second winding of motor H tobe energized with a current having such a phase in respect to theconstantly energized winding of the motor II that the arm I is driven ina counterclockwise direction to move the heat controlling valve towardsopen position. Such movement of the driven arm I0 moves slider 36 alongthe balancing resistance 32 towards its right-hand end. When the drivenarm I0 and therefore the heat control valve reach such a position thatthe movement of slider 36 along balancing resistance 32 has rebalancedthe bridge circuit, the electronic amplifier 38 will deenergize thesecond winding of motor II, whereupon rotation of such motor will cease.The heat controlling valve has thus been partially opened as a result ofthe fall in temperature. If further temperature fall should occur in theaircraft, the driven arrn I0 will move further in a counter-clockwisedirection. When the minimum desired temperature in the aircraft isreached, the arm I0 will-have been moved to its other extreme positionwherein it engages a stop pin 56 carried by the base plate I4. In thisposition, the Contact slider 36 will be at the extreme right-hand end 0fbalancing resistance 32 in order to rebalance the bridge circuit 26 andthe heat control valve is fully open.

Similarly, upon a subsequent temperature rise, the resistance oftemperature sensitive resistance 21 will increase. This will unbalancethe bridge circuit 26 in the opposite direction whereupon the electronicamplifier 38 will energize the second winding of motor II with a currentof opposite phase whereby the motor II will rotate in the oppositedirection. The driven arm I0 will therefore rotate in a, clockwisedirection and carry with it slider 36 which, in cooperation withbalancing resistance 32, will rebalance the bridge circuit f to causedeenergization of the second winding of the motor II. Such movementoperates the heat control Valve towards closed position.

From the foregoing, it will be clear that the driven arm I 0 andtherefore the heat control valve are normally automatically graduatinglypositioned in accordance with the temperature condition to which thetemperature sensitive resistance 21 responds.

The apparatus thus far described may become inoperative for any numberof reasons. Under such conditions, it is highly desirable that the heatcontrol valve can be manually positioned entirely independently of thepower driving means. To this end, a manual operator 60 is provided whichis journalled on or concentrically with the shaft I3. This manualoperator 60, as shown, lies directly in back of the plate I8 of whichthe driven arm I0 is an extension. 'I'he manual operator 6U has a manuallatch 6| pivoted thereon at 62. The manual latch 6| is provided with alatching portion 63 that is adapted to engage a notch 64 formed in theplate I8. A biasing spring 65, having one end secured to the manuallatch 6I and its other end secured to the manual operator 60, biases themanual latch 6I in such direction thatl the latching portion 63 engagesthe periphery of the plate I8 and enters the notch 64 when brought intoregistry therewith. Moreover, thev opposite end of the manual latch 6Iis provided with a cam surface 66 which engages the stop 55 when themanual operator is in the extreme position shown. Under such conditions,the latching portion 63 of the manual latch 6I is retracted, as shown,against the bias of spring 65. 'Ihe manual latch 6| is further providedwith a cam portion 61. This cam portion 61 cooperates, under certainconditions, with a pin 68 carried by and extending backwardly from thedriving latch 2|.

Whenever it is desired to operate the driven arm I0 manually and toprevent its actuation by the power means II, the manual operator 6|] ismoved in a clockwise direction. Initial movement of the manual operatorremoves the cam surface 66 from the stop pin 55, whereupon spring movesthe latching portion 63 of the manual latch 6I into engagement with thecircular periphery of the plate I 8. Upon further clockwise movement ofmanual operator 60 to an extent determined by the position 0f the drivenarm IIl at the timey manual control is desired, the cam 61 will rideunder the pin 68 and lift the latching portion 23 of the driving latch2| out of the notch 24 in plate 20. At the same instant, the latchingportion 63 of the manual latch 6| will be pulled into the notch 64 bythe biasing spring 65. The driven arm I0 isthus disconnected from thedriving arm I5 and is connected to the manual operator 60. The amount ofmovement of'manual operator 66 necessary to accomplish this declutchingof the driving arm I5 and clutching of the manual operator 60 willdepend upon the position of driven arm I0 at the time it is desired totake manual control. However, by moving manual operator 60 throughoutits full range of movement, just once, the operator will be assured thatsuch uncoupling and coupling action has been accomplished. Thereafter,he may position the manual operator 60 in any desired position and thedriven arm I0 will assume a similar position. In such positioning of themanual operator 60, the notch 24 may again pass under the latchingportion 23 of the driving latch 2|. But no re-engagement of the partscan take place under the bias of spring 25 since the cam 61 will againengage the pin 68 and prevent movement of the latch ing portion 23 intothe notch 24.

In order to return control of the driven arm Ill to the motor II it isnecessary to unlatch the manual operator 6|! and relatch the drivinglatch 2|. It will of course be understood that these various latcheswill be inaccessible in a complete assembly which will include the usualhousing or covering members. Therefore, the only way of unlatching themanual latch 6I is to return the manual operator 60 to the positionshown wherein the coacticn of cam surface 66 with stop pin 55 retractsthe latching portion 63 of the manual latch 6 I as shown in the drawing.When such retracting action takes place the notch 24 in the plate 20which is secured to the driven arm I0 will be quite near the stop 55.There is no assurance however that the latching portion 23 of thedriving latch 2| will'be in registry with the notch 24 at such time.Means is therefore provided to automatically drive the arm I5 andtherefore the latch 2|. to a predetermined position whenever the manualoperator 6|) is moved out of its normal inactive position in which .itis shown, provided of course that the motor II is operative.

In the particular embodiment herein disclosed, this automaticpositioning of these parts in a predetermined position is accomplishedby unbalancing the bridge circuit 26. It will be rcmembered that the onearm of the bridge circuit 36 includes the fixed resistance 3| which wassaid to be normally shorted. This resistance 3| is normally shorted by aswitch comprising switch arms 10 and secured to the base plate I6. Theswitch arm ll is biased in a direction to disengage its contact '|2 fromthe cooperating contact 'i3 carried by the switchV arm 10. Normally,such disengagement is prevented when the manual operator 60 is in itsnormal or inactive position. This may be accomplished, for example, byproviding the manual operator 6U with a pin 'i4 of insulating materialthat engages the switch arm l and forces contact l2 into engagement withcontact I3 when the manual operator 55 is in its normal or inactiveposition. With these contacts closed, there is a shunt circuit about theresistance 3| comprised by wire l5, switch arm lo, contact i3, contact'|2, switch arm li, and wire i6. Upon initial movement of manualoperator 6G out of its normal or inactive position then, not only doesthe cam surface 66 move away from stop pin 55 but in addition the pin'iii moves away from switch arm '1| permitting contact l2 to separatefrom contact '13. This removes the shunt around resistance 3| so thatthis resistance is then included in that arm or" the bridge circuitwhich includes the Xed resistance 3G. Increasing the resistance of thisarm has the same effect as a decrease in resistance of the temperaturesensitive resistance 2l. In other words, it has the same effect as afall in temperature on the automatic control system. The resistance 3|is made large enough so that removal of the shunt will demand that thedriving arm i5 move to its extreme position, regardless of the actualtemperature, wherein the driven arm l should engage stop pin 56 and theheat control valve would be wide open if these parts were latchedtogether. This means that if the automatic control system is operativeupon movement of manual operator 60 out of its inactive or normalposition, the motor I will drive the arm I counter-clockwise to itsopposite extreme position wherein the notch 24 of plate will be inregistry with the latching portion 23 of latch 2l when the manualoperator 60 has been returned to its normal or inactive position whereinthe latching portion 63 of the manual latch 6| is in. its retractedposition. If the automatic control system is inoperative at the timethat manual operator 6l) is initially moved out of its inactiveposition, the arm |5 will remain in whatever position it was at suchtime. Under these conditions, no automatic recoupling of the automaticmechanism to the driven arm |0-can take place regardless of the positionto which the manual operator B0 is moved. However, just as soon as theautomatic control system becomes operative and so long as the manualoperator 6U is out of its inactive position, the arm l5 and drivinglatch 2| will be moved to the extreme position wherein it is ready forautomatic relatching upon return of the manual operator to its inactiveposition.

'From the foregoing it will be evident that the single manual operator60 is operative to perform a number of functions in a fool-proof manner.So long as it remains in its normal or inactive position, the driven armI0 is under the control of the motor Il and the automatic system ofcontrol, Then, upon a full movement of the manual operator 60 to itsother extreme position, the driving latch 2| will be disengaged and themanual latch 6| will be engaged irrespective of the position of thedriven arm IU at such time. Thereafter, the manual operator 60 may beplaced in any desired position except the extreme position shown, and

moved as often and as far as desired and the driven arm Il) will assumea corresponding position. However, when the automatic control systemagain becomes operative, the motor means will drive the driving arm I5to such position that automatic recoupling of the driving arm I5 to thedriven arm I0 will take place when the manual operator B0 is next movedback to its normal lnactive position as shown. Even though the automaticcontrol system has become operative again so that the arm l5 is in itsopposite extreme position ready for automatic recoupling, and eventhough such automatic recoupling takes place by movement of the manualoperator S0 to the p0- sition shown, if it is still desired to havemanual control, subsequent movement of the manual 0perator 6U out of itsinactive position will again unlatch the driving latch 2| by the passageof cam 57 under pin S8 and the manual operator will pick up the drivenarm I0 since the right-hand end of latch member 6I will engage thesurface provided by the extension `8| of the plate I8.

It should be noted that a biasing spring B2 has been shown indicatingthat the driven arm I0 is biased towards the stop pin 56. This is forthe following reasons. If the manual arm l0 were biased in the oppositedirection and the manual operator l6|) were moved to the position shownwhile the driven arm 0 is being controlled manually, the driven arm I0under such conditions would be engaging the stop pin 56. At this time,the latch portion 63 would be retracted due to the engagement of camsurface :6B with stop pin 55. Under such conditions, neither the manualoperator 6U nor the driving arm l5 would be coupled to the driven arml0. The driven arm l0 therefore if provided with the opposite bias wouldbe moved clear over into engagement with stop pin 55 although the manualoperator 60 is in the position demanding that the driven arm Ill be inengagement with stop pin 56. For this reason, a bias should be appliedto the driven arm IIJ in the direction indicated or the driven arm Illshould have no bias on it whatsoever.

From the foregoing, it will be seen that I have provided a novelmechanism whereby a device that is normally positioned through a powermeans may be positioned manually entirely independently of such powermeans. Furthermore, I have provided such a mechanism which is especiallyvaluable in connection with aircraft or the like where dependabiilty,simplicity, and a minimum number of operations are desirable so that theapparatus is fool-proof and manual control can be taken oversubstantially instantaneously with the minimum number of operations. Itwill further be apparent that while I have disclosed my invention inconnection with the control of temperature in an aircraft, it is equallywell useable in any situation where it is desired to take over manualcontrol independently of the power means of any device that is normallyoperated by the power means, whether such power means operation isautomatic or otherwise. Furthermore, the particular type of power meansemployed and the manner in which the power means is controlled isrelatively unimportant in so far as the basic features of my inventionare concerned. Many changes and modifications will occur to thoseskilled in the art without departing from the spirit of my invention,and I therefore intend to be limited only by the scope of the claimsappended hereto.

I claim as my invention:

1. In a. temperature control system, in combina.-

tion. a variablybie for chang'- lng a temperature condition, a poweroperator f bysaid manual operator, and meansoperable 'as an incident tomovement oi said manual operator out otite normal position'toadditionally control said power operator to render said power loperatorincapable of positioning said member in said plurality oi positions uponsaid changein temperature Z'ln a apparatus, in combination,

'a member to be positioned, a power operator to operator to said extremeposition.

5. In a positioning apparatus, in combination.V

posltioiisaid lmember', a manual operator having v a normal stationaryposition in which it remainsduring'operction of said member by saidpower operator, means operable upon movement o f said manual operatorout Vof its normalv stationary position to position said member and toprevent further positioning of said member by said power operatorj 'toreturn control of said member to said power operator only when saidpower operator and manual operator are in predetermined p0- sitions, andmeans operable `as an incident to movement lof said manual operator outof said normal stationary position to cause movement of said poweroperator to said predetermined posi- 3. In a positioning apparatus, incombination, a member to be positioned, a power operator to positionsaid member, a manual operator having a normal stationary position inwhich it remains during operation of said member by said Power operator,means operable upon movement of said manual operator out of its normalStationary position to position said member and to prevent furtherpositioning of said member by said power operator, means to returncontrol of said memberV to said power operator only when said poweroperator is in a predetermined position and said manual operator isreturned to its normal sta- D ticnary position whereby manual control ofsaid member can be maintained so long as said manual member is notreturned to said normal stationary position, and means operable as anincident to movement of said manual operator out of said l normalstationary position to move said power operator to said predeterminedposition.

4, In a positioning apparatus, in combination, a member to bepositioned, a, power operator to position said member, a manual operatorhaving a normal stationary position in which it remains during operationof said .member by said power operator, means operable upon. movement ofsaid manual operator out of its normal stationary position to positionsaid member and to prevent further positioning of said member by saidpower operator, means to return control of said member to said poweroperator only when said Power operator is in one oi its extremepositions and said manual operator is returned to its normal stationaryposition whereby manual control of said member can be maintained so longas said manual member is not returned to said normal stationaryposition, and means operable as an incident to movement of said manualoperator out of said normal stationary position to move a member to bepositioned, a power operatorV to position said member, a manual operatorhaving a normal stationary position in which it remains during operationof said member `by said power operator, means operable upon movement ofsaid manual operator out of its normal stationary position to positionsaid member and to prevent further positioning 'of said member by saidpower operator, means to return control of said member to said poweroperator only when said power op(- erator is in a position such'as tonormally' place said.-member in a position corresponding to the positionit is moved to by-said manual operator 'when the manual operator iscontrolling said member and is movedto its normal stationary position,andv means Operable as an incident to` movement of said manual operatorout of its 1 normal position to cause movement of said power operator tosaid' position.

6. 1n a positioning system, electric: motor means, an electrical networkin control of said i motor means, control means operable on said networkVto cause motor operation, a member to 'be positioned driven by saidmotor means, electrical means actuated by said member and cooperatingwithsaid network to stop motor operation when said member reachesv aPosition commensurate with the condition of said control means, amanual-operator, and means operable thereby to preventfurtherpositioning of said member by said motor means, to causepositioning of said member by said manual operator, andV to influencesaid network in a manner to drive said motor means to a predeterminedposition. Y

'7. In combination, Va .member to be positioned,

a power operator, a. pivoted manual operator movable in a single planeand having a normal stationaryl position, clutching means normallyclutching said power operator to said member, means operable uponvmovement of said manual operator about its pivot out of its normalstationary position to declutch said member from said power operator andto clutch it to said manual operator in a predetermined relationship forpositioning thereby upon movements thereof about its pivot after saiddeclutching and clutching actions have taken place, the position of saidmanual operator thereafter indicating the position of said member, andmeans associated with Y said manual operator to cause declutchng thereofand reclutching of said power operator.

8. In combination, a member to be positioned, a. power operator, amanual operator having a normal stationary position, clutching meansnormolly clutching said power operator to said memher, means operableyupon movement of said manual operator out of its normal stationaryposition to declutch said member from said p ower operator and to clutchit to said manual operator for' positioning thereby upon movementsthereof after said declutching and clutching actions have taken place,means for reclutching said member to said power operator, said meansbeing eiective only upon return of said manual operator to its normalstationary position andkmovement of said power operator to apredetermined position, and means to so position said power operatorautomatically as a result of declutching of said power operator fromsaid member.

9. In a positioning system, in combination, a member to be positioned ina plurality of positions, o, power operator therefor operable toposisaid Y tion said member in a plurality of positions, means tocontrol said power operator to position said member in a plurality oi'positions, a manual operator movable to a plurality of positions, clutchmeans operable to connect said manual operator to said member to bepositioned only in a predetermined relation whereby the position of saidmanual operator when clutched to said member to be positioned indicatesthe position of said member, and means operable upon movement of saidmanual operator from a predetermined position 'to prevent furtherpositioning of said member by said power operator until said manualoperator is returned to said predetermined position.

l0. 1n a device of the class described, a memoer .to be positioned,power means for positioning said member, manual means having a normalpredetermined position, clutch means for connecting said manual means tosaid member only in a predetermined relationship whereby the position ofsaid manual means thereafter indicates the position of said member, andmeans operable as an incident to movement of said manual means out ofsaid normal predetermined position to influence Subsequent operation ofsaid power means.

1l. In a positioning mechanism, in combination, e. device to bepositioned, reversible electric motor means connectable thereto forpositioning the same, manual means movable to a plurality of positionsconnectable to said device for positioning the same, and connectingmeans for selectively and independently connecting either said manualmeans or said reversible motor means t said device, said connectingmeans including mechanically interengaging portions by which said manualmeans and device can only be connected together in a predeterminedrelationship such that each one of the plurality of positions to whichsaid manual means may be moved indicates the position of said deviceregardless of the position of said device at the time said manual meanswas connected thereto.

12. In a positioning mechanism, in combination, a device to bepositioned in a plurality of positions and arranged to remain in anyposition to which it is moved, reversible electric motor meansconnectable to said device for driving the same back and forth toposition it in a plurality of positions, electrical means to controlsaid reversible electric motor means, manual means movable in agraduated manner over a limited rane commensurate with the desiredmovement of said device, and connecting means for selectively andindependently connecting either said manual means or said reversiblemotor means to said device, said connecting means including mechanicallyinterengaging members for connecting said manual means and said devicein a predetermined relationship such that the position of said manualmeans in its limited range of movement during manual operationpositively indicates the position of said device regardless of theposition of said device at the time said manual means was connectedthereto.

RUSSELL H. WHEMPNER.

REFERENCES CITED The following references are of record in the iile ofthis patent:

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